Description:
------------
It would be nice if PHP had a builtin "which" command.
For example, which("ffmpeg") would allow the user to check whether ffmpeg
was installed, prior to calling it with exec().
Test script:
---------------
which("ffmpeg") should return eg:
/usr/bin/ffmpeg
if the command exists, and is in the £PATH for exec(), or
false
if it doesn't exist.

Thanks for your quick reply. I agree - it's trivial to do in userspace.
The simplest way is just to
$lastline = exec ("which $ffmpeg", $output, $retval)
if (retval){
return ($lastline)
}else{
return ($false)
}
Indeed many of the PHP functions are trivial in that sense - one could build file_get_contents() out of fopen(),file(),fclose(), or could avoid using unlink by a call to system("rm filename").
However the attraction of PHP is that so many of the required functions already exist and I don't have to write them. So I think that which() would be a useful addition.
I'm particularly thinking of the cases where php-cli is an improvement on shell-scripting.

Using exec is definitely not the best way to do that one. Anytime you fork+exec a
new process you take on a significant performance penalty. Same goes for your
system() example. But, if you can do it in a couple of lines without resorting to
an exec(), then it is indeed trivial. file_get_contents() is slightly more
complicated because of the streams support in it.